Thread: 7mm wsm to 270wsm sizing

Originally Posted by dannyb

@grandpamac I feel like if anyone knows a way you might ? Any suggestions ?

Greetings dannyb,
If the .270 WSM brass has just been necked up to 7mm and has not been fired then there should be no problem in necking it back down. You should check if the shoulder has been moved forward. You can do this with a comparitor. The difference in length to the shoulder is 0.038" or 0.96mm longer for the 7mm WSM. The fired stuff is a different matter. If the cases were just necked up without forming a false shoulder and fired in a 7mm WSM chamber then they would have been fired in a chamber with grossly excessive head space. This could have weakened the case body just ahead of the web and can lead to a head separation. To be safe these should be binned.
Regards Grandpamac.

Originally Posted by grandpamac

Greetings dannyb,
If the .270 WSM brass has just been necked up to 7mm and has not been fired then there should be no problem in necking it back down. You should check if the shoulder has been moved forward. You can do this with a comparitor. The difference in length to the shoulder is 0.038" or 0.96mm longer for the 7mm WSM. The fired stuff is a different matter. If the cases were just necked up without forming a false shoulder and fired in a 7mm WSM chamber then they would have been fired in a chamber with grossly excessive head space. This could have weakened the case body just ahead of the web and can lead to a head separation. To be safe these should be binned.
Regards Grandpamac.

That's very helpful as I have 30 virgin cases that have been necked up to 7mm but unfired so these at least should be salvageable for me

Unfortunately or fortunately for @223nut I also have 50 cases that have been fired so looks like he's got some extra brass